PowerSat Corporation has filed 2 important patents. One uses the solar array to propel itself from low earth orbit to geostationary orbit. The other one turns a cloud of small geostationary solar power satellites into a huge phased array. The propulsion patent plausibly reduces launch costs by 67%. The satellite cloud microwave phasing patent, however, has a huge hidden benefit that I doubt even Powersat has fully taken into account: industrial learning curve of small launchers.

A similar argument has been made before by Autodesk founder, John Walker in "A Rocket A Day keeps the High Costs Away. Basically, if you are going to deploy a system with a large number of repetitions, the total (integral) cost is given by the formula: firstunit*(units^(1-rate))/(1-rate). To replace all fossil fuel baseload generation capacity in the US (250GW) would require 20,000 Falcon 9 HL launches (78Mdollars/15000kg or $5200/kg to geostationary transfer orbit) each orbiting 3 BrightStars (PowerSat's satellite) at nearly 5000kg each. Walk that down down an industrial learning curve at 10% per doubling, the total launch cost of a 250GW cloud would be (1-.67)*5200*3*5000*(20000^(1-.1))/(1-.1) = 212G$ or less than a dollar per installed watt of baseload electric generation capacity.

So the ability to launch small, standard modules independently has an enormous impact on the primary historic barrier to solar power satellites.

But what about the satellite itself?

Assuming 10% energy loss in transmission to the ground array, each satellite would need to generate less than 1kW/kg (around 250GW/(3*5000*200*100)kg/(1-.1)) or 5MW/satellite. This is similar to the specific power estimate arrived at in "Low Mass Solar Power Satellites Built From Terrestrial or Lunar Materials", S. D. Potter, SSI Update, Volume XX, Issue 1 (1994). Briefly, at 35% solar conversion efficiency and 1kW/m^2 solar flux most of that satellite would be in a weightless mirror that would have to be about 140m in diameter at some fraction of 350g/m^2 (5000kg/(5MW/(.35*1kW/m^2))). Weightless mirrors can be very low mass and inexpensive.